JP2014099235A - Magnetic recording medium and hard amorphous carbon film for magnetic head containing ultra small amount of hydrogen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium and a hard amorphous carbon film for magnetic recording head containing an ultra small amount of hydrogen.SOLUTION: A magnetic recording medium of one embodiment includes: at least one ground layer formed on a nonmagnetic substrate; a magnetic recording layer formed on the ground layer; and an overcoat formed on the magnetic recording layer. The overcoat is an amorphous carbon layer in which a ratio of spbond with respect to spbond (sp/( sp+ sp)) is at least 0.5 in a film thickness direction of the overcoat. A hydrogen content of the overcoat at the center layer in the film thickness direction thereof is 0.1 atm.% to 0.6 atm.%. Further, a device and a method are also provided.

Description

  The present invention relates to a data storage system, and in particular, the present invention relates to various components of a magnetic storage system having an ultra-hard amorphous carbon film and a method for forming the same.

  The core of the computer is a magnetic hard disk drive (HDD). A typical magnetic hard disk drive is a rotating magnetic disk, a slider having a read / write head, a suspension arm positioned above the rotating disk, and a read and / or write head selected on the rotating disk by moving the suspension arm about its axis. Including an actuator arm disposed on a circular track. The suspension arm is biased so that the slider comes into contact with the disk surface when the disk is not rotating. However, when the disk rotates, the suspension arm moves near the air bearing surface (ABS) of the slider. As a result of the air swirling, the slider is placed on the air bearing at a slight distance from the rotating disk surface. When the slider rests on the air bearing, the read / write head is used to write magnetic impressions on the rotating disk and read magnetic signal fields from the rotating disk. The read / write head is connected to a processing circuit operated by a computer program for executing a read / write function.

  The amount of information processing in the information age is increasing rapidly. In particular, HDDs are desired to store more information in its limited area and volume. One technical method for this demand is to increase the capacity by increasing the recording density of the HDD. In order to achieve a higher recording density, further downsizing of the recording bits is effective. Usually, however, this requires the design of further smaller components.

  However, further miniaturization of the various components itself has a series of problems and obstacles.

  As described above, in a magnetic disk drive, a magnetic head is used for recording or reproducing information on a magnetic disk (magnetic recording medium). When the magnetic spacing becomes narrower, the magnetic head and the magnetic disk can be brought closer to each other, information can be recorded in a minute area, and a minute magnetic signal on the magnetic disk can be reproduced. When the spacing between the head and the disk is narrow, it is necessary to reduce the film thickness of the magnetic disk and the overcoat of the magnetic head.

  However, the overcoat must be chemically stable, dense and uniform to prevent corrosion of the metal used in the recording layer of the magnetic disk and in the recording and reproducing elements of the magnetic head. is there. Furthermore, if the magnetic head is very close to the magnetic disk, a sufficiently high wear resistance must be present due to the relative rotational movement. Further, generally, as the conventional overcoat of magnetic disks and magnetic heads becomes thinner, the corrosion resistance decreases due to a decrease in coverage, a decrease in effective hardness, and a decrease in wear resistance. Therefore, in order to make the magnetic disk and magnetic head overcoat thinner while maintaining corrosion resistance and wear resistance, it is necessary to improve the density and hardness of the magnetic disk and magnetic head overcoat, and the thinner film It is necessary to eliminate the deterioration caused by the thickness.

  In order to improve the recording density, the suppression of thermal demagnetization of the recording medium and the maintenance of the writing characteristics should be satisfied at the same time. In order to achieve a high recording density, the bit diameter of the recording medium should also be on the order of nanobits. However, as the bit diameter decreases, the problem of thermal demagnetization arises.

  Information recorded on the recording medium is lost due to thermal magnetization fluctuations over time, which causes thermal demagnetization. In order to solve the problem of thermal demagnetization, the thermal stability of magnetization can be improved by using a material having high magnetic anisotropy. However, if the magnetic anisotropy becomes too high, it becomes impossible to reverse the magnetization of the recording medium by the recording magnetic field from the magnetic head recording element, and as a result, the magnetic medium can no longer be written.

  In particular, in order to improve the surface recording density, a new technique for simultaneously realizing both the suppression of thermal demagnetization and the maintenance of the writing property to the recording medium is indispensable. One method that has been proposed to solve this problem is thermally assisted recording (TAR). In this technique, magnetic recording is performed while reducing the coercive force by temporarily and locally heating the recording medium. By using this technique, even a recording medium having high magnetic anisotropy can be written. As a result, the suppression of thermal demagnetization and the maintenance of the writing property to the recording medium are satisfied at the same time, and a large increase in surface recording density can be realized. Accordingly, the heat resistance of the overcoat of the magnetic disk and the magnetic head is required.

  In particular, the development of a technique for improving the heat resistance of a head-disk interface (HDI) is important for creating a practical TAR method. The conventional HDI is composed of a magnetic head overcoat, a magnetic disk overcoat, and a lubricating film, each of which plays a role in preventing head and disk corrosion and wear and maintaining high reliability of the magnetic disk drive. . However, the structural element of HDI has carbon as a main component, and is considered to be more susceptible to heat than metal or ceramic. Thus, in a TAR high temperature environment, HDI structural elements are typically deformed and / or degraded by heat. As a result, degradation and deformation become a problem in the reliability of the magnetic recording system.

Conventional diamond-like carbon (DLC) films are used as disk overcoats for HDI structural elements. However, in a high temperature environment where application to TAR is considered, as the distance between the head and the disk becomes narrower, mechanical resistance and chemical resistance are required, and at the same time, for desirable results, Stability is also required. Thus, a desirable DLC film property is an overcoat having a high film density, ie, improved sp ³ bonds (eg, a diamond-type structure).

However, since the DLC film manufactured by the conventional sputtering method has a structure close to that of graphite, there are few sp ³ bonds. Furthermore, since the DLC film formed by chemical vapor deposition (CVD) contains hydrogen in the film because a hydrocarbon gas is used as a raw material, it is difficult to achieve a high sp ³ bond ratio by this method. .

  As described above, in order to achieve a higher recording density of the magnetic disk drive, a thinner shape and higher heat resistance are required for the overcoat of the magnetic disk and the magnetic head. In order to ensure higher reliability as a magnetic disk drive, higher density, hardness, and higher heat resistance are desired.

  Therefore, in order to produce thinner films, it is beneficial to develop a system with high recording density by improving corrosion resistance and wear resistance. Furthermore, in order to improve the practicality on TAR mounting, improvement in heat resistance can be beneficial.

A magnetic recording medium according to one embodiment includes at least one ground layer on a nonmagnetic substrate; a magnetic recording layer on the ground layer; and an overcoat on the magnetic recording layer, the overcoat against sp ² bonds. An amorphous carbon film having a sp ³ bond ratio (sp ³ / (sp ² + sp ³ )) of at least 0.5, and a hydrogen content in a central layer of the overcoat in the film thickness direction of the overcoat Is 0.1 atomic% to 0.6 atomic%.

A magnetic head according to another embodiment includes a read element; and an overcoat on the side where the read element faces the medium, the overcoat having a ratio of sp ³ bonds to sp ² bonds (sp ³ / ( sp ² + sp ³ )) is at least 0.5, and the hydrogen content in the amorphous carbon film of the central layer of the overcoat in the film thickness direction of the overcoat is 0.1. It is characterized by being atomic% to 0.6 atomic%.

  Any of these embodiments includes a magnetic head, a drive mechanism for passing a magnetic medium (eg, a hard disk) over the magnetic head, and a controller electrically coupled to the magnetic head. It can be realized in a magnetic data storage system such as a system.

According to yet another embodiment, a method includes forming an overcoat on at least one top of a magnetic layer of a magnetic medium and a side of the read element facing the medium, the overcoat comprising sp for sp ² bonds. ^An amorphous carbon film having a ratio of ^three bonds (sp ³ / (sp ² + sp ³ )) of at least 0.5, and an amorphous carbon film of a central layer of the overcoat in the film thickness direction of the overcoat The hydrogen content in the overcoat is characterized in that the hydrogen content in the overcoat regulates the hydrogen gas flow into the film deposition chamber during the overcoat deposition Then, the hydrogen gas pressure in the film deposition chamber is adjusted to be within the above range.

  Other aspects and advantages of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrates examples of the principles of the invention.

  For a fuller understanding of the nature and advantages of the present invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.

1 is a simplified diagram of a magnetic recording disk drive system. It is the schematic of the cross section of the recording medium using a longitudinal direction recording system. 2B is a schematic diagram of a combination of a conventional magnetic recording head and recording medium for longitudinal recording as in FIG. 2A. FIG. This is a magnetic recording medium using a perpendicular recording system. It is the schematic of the combination of the recording head and recording medium for one side perpendicular | vertical recording. 1 is a schematic view of a recording apparatus adapted to separately record on both sides of a magnetic recording medium. 2 is a cross-sectional view of one particular embodiment of a perpendicular magnetic head having a helical coil. FIG. FIG. 6 is a cross-sectional view of one particular embodiment of a piggyback magnetic head having a helical coil. 2 is a cross-sectional view of one particular embodiment of a perpendicular magnetic head having a loop coil. FIG. 2 is a cross-sectional view of one particular embodiment of a piggyback magnetic head having a loop coil. FIG. It is a fragmentary sectional view of the magnetic recording medium in one embodiment. 2 is a process flowchart of a method in one embodiment. It is a graph which shows the measurement result of the film | membrane density with respect to the hydrogen content in the film | membrane in one Embodiment. It is a graph which shows the measurement result of the film | membrane hardness with respect to the hydrogen content in the film | membrane in one Embodiment. It is a graph which shows the measurement result of the residual film thickness of the carbon film with respect to the heating time in one Embodiment. It is a graph which shows the measurement result of the hydrogen content of the super-hard amorphous carbon film in one embodiment. FIG. 11A is a graph showing the measurement results of the hydrogen content of several types of ultra-hard amorphous films in one embodiment. FIG. 11B is a detailed view of the graph of FIG. 11A showing the measurement results of the hydrogen content of the ultra-hard amorphous carbon film in one embodiment. It is the schematic of the vapor phase growth apparatus which uses the arc discharge in one Embodiment.

  The following description is provided for the purpose of illustrating the general principles of the invention and is not meant to limit the inventive concepts claimed herein. Furthermore, certain features described herein can be used in combination with features described separately in each of the various possible combinations and permutations.

  Unless otherwise defined herein, all terms have their meanings as defined herein and their meanings as understood by one of ordinary skill in the art and / or meanings defined in dictionaries, articles, etc. The widest possible interpretation is given.

  It should also be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include the plural unless specifically stated otherwise. is there.

  In the following description, several preferred embodiments of disk-based storage systems, and / or related systems and methods, and their operation and / or components are disclosed.

In one general embodiment, a magnetic recording medium includes at least one ground layer on a nonmagnetic substrate; a magnetic recording layer on the ground layer; and an overcoat on the magnetic recording layer, the overcoat comprising , The ratio of sp ³ bond to sp ² bond (sp ³ / (sp ² + sp ³ )) is at least 0.5, and the overcoat in the film thickness direction of the overcoat The hydrogen content in the central layer is 0.1 atomic% to 0.6 atomic%.

In another general embodiment, the magnetic head includes a read element; and an upper overcoat on the side where the read element faces the medium, the overcoat having a ratio of sp ³ bonds to sp ² bonds. (Sp ³ / (sp ² + sp ³ )) is an amorphous carbon film having at least 0.5, and hydrogen content in the amorphous carbon film of the central layer of the overcoat in the film thickness direction of the overcoat The amount is 0.1 atomic% to 0.6 atomic%.

  Any of these embodiments includes a magnetic head, a drive mechanism for passing a magnetic medium (eg, a hard disk) over the magnetic head, and a controller electrically coupled to the magnetic head. It can be realized in a magnetic data storage system such as a system.

In one general embodiment, the method includes forming an overcoat on at least one of a magnetic layer of a magnetic medium and a side of the read element facing the medium, the overcoat comprising sp ² bonds. Is an amorphous carbon film having a ratio of sp ³ bonds to (sp ³ / (sp ² + sp ³ )) of at least 0.5, and the amorphous overcoat center layer in the overcoat film thickness direction. The hydrogen content in the carbon film is from 0.1 atomic% to 0.6 atomic%, and the hydrogen content of the overcoat is determined by the flow of hydrogen gas into the film deposition chamber during the overcoat deposition. By adjusting the hydrogen gas pressure in the film deposition chamber.

  Referring now to FIG. 1, a disk drive 100 according to one embodiment of the present invention is shown. As shown in FIG. 1, at least one rotatable magnetic disk 112 is supported on a spindle 114 and rotated by a drive mechanism that can include a disk drive motor 118. The magnetic recording on each disk is typically in the form of an annular pattern (not shown) of concentric data tracks on the disk 112.

  At least one slider 113 is disposed near the disk 112, and each slider 113 supports one or more magnetic read / write heads 121. As the disk rotates, the slider 113 moves radially inward and outward over the disk surface 122 so that the head 121 records different tracks of the disk on which the desired data is recorded and / or written. Can be accessed. Each slider 113 is attached to the actuator arm 119 by a suspension 115. The suspension 115 applies a slight spring force that biases the slider 113 with respect to the disk surface 122. Each actuator arm 119 is attached to an actuator 127. The actuator 127 shown in FIG. 1 may be a voice coil motor (VCM). The VCM includes a coil that can move in a fixed magnetic field, and the direction and speed of movement of the coil is controlled by a motor current signal supplied by the controller 129.

  During operation of the disk storage system, rotation of the disk 112 creates an air bearing between the slider 113 and the disk surface 122, thereby exerting an upward force or lift on the slider. Thus, during normal operation, the air bearing balances the slight spring force of the suspension 115 and supports the slider 113 slightly above and away from the disk surface at a narrow, substantially constant interval. Note that in certain embodiments, the slider 113 can slide along the disk surface 122.

  The various components of the disk storage system are controlled in operation by control signals generated by the controller 129, such as access control signals and internal clock signals. The control unit 129 typically includes logic control circuitry, storage (eg, memory), and a microprocessor. The control unit 129 generates control signals that control various system operations such as drive motor control signals for line 123 and head position and seek control signals for line 128. The control signal for line 128 provides the desired current profile for optimally moving and placing the slider 113 on the desired data track of the disk 112. Read and write signals are communicated to read / write head 121 by way of recording channel 125.

  The foregoing description of a typical magnetic disk storage system and the accompanying description of FIG. 1 are for representation purposes only. It will be apparent that a disk storage system can have multiple disks and actuators, and each actuator can support multiple sliders.

  It also provides an interface for communication between the disk drive and the host (internal or external) to send and receive data and to control the operation of the disk drive and communicate the status of the disk drive to the host All of which will be understood by those skilled in the art.

  In a typical head, an inductive write head includes a coil layer embedded in one or more insulating layers (insulating stack), the insulating stack comprising a first pole piece layer and a second pole piece layer. Arranged between. A gap layer is formed between the first pole piece layer and the second pole piece layer by the gap layer on the air bearing surface (ABS) of the write head. The pole piece layers can be connected in the back gap. When current is passed through the coil layer, a magnetic field is generated in the pole piece. In order to write small magnetic field information in a track on a moving medium, such as in a circular track on a rotating magnetic disk, the magnetic field surrounds the ABS gap.

  The second pole piece layer has a pole tip portion extending from the ABS to the flare point, and a yoke portion extending from the flare point to the back gap. The flare point is where the second pole piece begins to spread (flare) to form the yoke. The position of the flare point directly affects the magnitude of the magnetic field generated to write information on the recording medium.

  FIG. 2A schematically shows a conventional recording medium such as that used with a magnetic disk recording system as shown in FIG. This medium is used to record magnetic impulses on the surface of the medium itself, parallel to the surface of the medium itself. The recording medium, in this case a recording disk, basically comprises a support substrate 200 of a suitable non-magnetic material such as glass and has an upper layer coating 202 formed of a suitable conventional magnetic layer.

  FIG. 2B shows the operational relationship between a conventional recording / reproducing head 204, which may preferably be a thin film head, and a conventional recording medium as in FIG. 2A.

  FIG. 2C schematically shows the direction of the magnetic impulse substantially perpendicular to the surface of the recording medium used with the magnetic disk recording system as shown in FIG. In such perpendicular recording, the medium typically includes a lower layer 212 formed of a material having high magnetic permeability. This lower layer 212 is then provided with an upper coating 214 preferably made of a magnetic material having a higher coercivity than the lower layer 212.

  FIG. 2D shows an operational relationship between the vertical head 218 and the recording medium. The recording medium shown in FIG. 2D includes both the high permeability lower layer 212 described with respect to FIG. 2C above and the upper coating 214 of magnetic material. However, both of these layers 212 and 214 are shown attached to a suitable substrate 216. There is also an additional layer (not shown), typically referred to as an “exchange-break” layer or “intermediate layer” between layers 212 and 214.

  In this structure, the magnetic flux lines extending between the magnetic poles of the vertical head 218 loop in and out of the upper layer coating 214 of the recording medium having the lower magnetic permeability lower layer 212, so that the direction is substantially perpendicular to the medium surface. Information is transmitted to the upper coating 214 of magnetic material, which has a higher coercivity than the lower layer 212, in the form of a magnetized impulse with a magnetic flux line passing through the upper coating 214 and having a magnetization axis substantially perpendicular to the media surface. Is recorded. The magnetic flux is returned to the return layer (P 1) of the head 218 by the soft underlayer coating 212.

  FIG. 2E shows a similar structure, where the substrate 216 has layers 212 and 214 on each of the two opposite sides, adjacent to the outer surface of the magnetic coating 214 on each side of the media. A suitable recording head 218 is arranged so that recording can be performed on each side of the medium.

  FIG. 3A is a cross-sectional view of a perpendicular magnetic head. In FIG. 3A, helical coils 310 and 312 are used to form a magnetic flux in the stitch pole 308, which is then sent to the main pole 306. Coil 310 shows a coil extending outward from the page, while coil 312 shows a coil extending in the page. The stitch pole 308 may be recessed from the ABS 318. An insulator 316 can surround the coil and support some elements. In the direction of media movement indicated by the arrow to the right of the structure, the media must first pass through the return pole 314 and then connect to the stitch pole 308, main pole 306, and wrap around shield (not shown). Can move through the trailing shield 304 and finally through the upper return pole 302. Each of these components has a portion that contacts ABS 318. ABS 318 is shown across the right side of the structure.

  Perpendicular writing is accomplished by passing the magnetic flux from the stitch pole 308 through the main pole 306 and then to the disk surface positioned towards the ABS 318.

  FIG. 3B shows a piggyback magnetic head having features similar to the head of FIG. 3A. Two shields 304, 314 are located on the sides of the stitch pole 308 and the main pole 306. Sensor shields 322, 324 are also shown. The sensor 326 is typically disposed between the sensor shields 322, 324. Sensor 326 can also have an overcoat 508 (described in more detail below) disposed thereon. The overcoat 508 can be disposed on the upper side of the other part of the head facing the medium.

  FIG. 4A is a schematic diagram of one embodiment using a loop coil 410, sometimes referred to as a pancake structure, for supplying magnetic flux to the stitch pole 408. Next, the stitch magnetic pole supplies this magnetic flux to the main magnetic pole 406. In this direction, the lower return pole is optionally used. An insulator 416 can surround the coil 410 and support the stitch pole 408 and the main pole 406. The stitch pole may be recessed from the ABS 418. In the direction of media movement, indicated by the arrow to the right of the structure, the media is stitched magnetic pole 408, main magnetic pole 406, trailing shield 404 that can be connected to a wraparound shield (not shown), and finally the top It moves past the return pole 402 (all of which may or may not have a portion that contacts the ABS 418). ABS 418 is shown across the right side of the structure. In some embodiments, the trailing shield 404 may contact the main pole 406.

  FIG. 4B shows another type of piggyback magnetic head having a structure similar to the head of FIG. 4A that includes a loop coil 410 that wraps to form a pancake-type coil. Sensor shields 422, 424 are also shown. The sensor 426 is typically disposed between the sensor shields 422, 424. The sensor 426 can also have an overcoat 508 (described in more detail below) disposed thereon. The overcoat 508 can be disposed on the upper side of the other part of the head facing the medium.

  3B and 4B, an optional heater is shown near the non-ABS side of the magnetic head. A heater (heater in the figure) may also be included in the magnetic head shown in FIGS. 3A and 4A. The position of the heater can be changed based on design parameters such as the position where the protrusion is desired and the thermal expansion coefficient of the surrounding layers.

  Various embodiments described and / or suggested herein provide film density, film height, and heat resistance of an amorphous carbon overcoat, also referred to herein as an ultra-hard amorphous carbon overcoat. Structures and / or methods for improvement can be provided. Furthermore, the embodiments described and / or suggested herein can preferably reduce the thickness of the overcoat of the magnetic disk and magnetic head. Further, the protective layer embodiments disclosed herein provide high thermal stability even with thermally assisted magnetic recording systems, thereby enabling higher recording densities for higher reliability. Become.

  The ultra-hard amorphous carbon overcoat in various embodiments can be formed by film deposition while supplying only a small amount of hydrogen, whereby a very small amount of hydrogen is introduced into the film. In contrast to conventional methods that are essentially free of hydrogen, carbon films having a hydrogen content within a preferred range have an improvement in film density of up to 20% or more in certain embodiments and a film height of at least 10%. It has been found that it is ideal for improving the reliability of magnetic recording media and / or magnetic heads because of improved and improved heat resistance.

  FIG. 5 illustrates a magnetic recording medium 500 according to one embodiment. As an option, the magnetic recording medium 500 of the present invention can be implemented with the features of any other embodiments described herein, such as the embodiments described with reference to other figures. However, it should be understood that such a magnetic recording medium 500 and others provided herein may be used in a variety of applications and may or may not be explicitly described in the illustrative embodiments described herein. / Or can be used in reordering. Further, the magnetic recording medium 500 provided herein can be used in any desired environment.

  Referring now to FIG. 5, the magnetic recording medium 500 may be a magnetic disk or any other suitable magnetic recording medium that will be apparent to those skilled in the art. As shown, the magnetic recording medium 500 preferably includes at least one ground layer 504, such as a soft underlayer (SUL), a magnetic recording layer 506, and an overcoat 508 disposed on top of the non-magnetic substrate 502. However, any number of additional layers may be included depending on the desired embodiment.

  In another embodiment, the overcoat may be an overcoat of a magnetic head according to any method provided herein, preferably having a read element (also referred to herein as a sensor). In one preferred method, the overcoat can be placed on top of the side where the read element faces the media (see overcoat 508 in FIGS. 3B and 4B). Further, the protective layer is in the surface facing the medium, the magnetic head is coplanar with and / or forms part of it, is offset from the surface, protrudes upwards, etc. It may be. In one method, the overcoat may be an overcoat of a magnetic head having an upper shield layer, a lower shield layer, and a reproducing element provided between these layers. Further, the overcoat may be an overcoat of a recording head having a lower magnetic pole, a main magnetic pole, a shield layer, and an auxiliary magnetic pole. Alternatively, the overcoat can include an air bearing surface overcoat, which can be formed on the surface of the read element opposite the magnetic media.

  In a further method, an overcoat can be provided on the top surface of both the head and the media.

  The following description provides further details regarding various embodiments of the overcoat, and such details generally apply to any overcoat described herein, such as an overcoat on the top surface of the head and / or media. Is possible.

The overcoat can be formed as an amorphous carbon film. Further, the amorphous carbon film may be primarily tetrahedral amorphous carbon, for example, but not limited to, greater than about 50 atomic percent (atomic percent). In one preferred method, the ultra-hard amorphous carbon film can have a high sp ³ bond ratio. According to an illustrative embodiment, the ultra-hard amorphous carbon film can have a sp ³ bond to sp ² bond ratio (sp ³ / (sp ² + sp ³ )) of at least about 0.5. (Preferably) may be larger or smaller depending on the desired embodiment.

  Referring to FIG. 5, an overcoat 508 on the surface of the media 500 is shown and discussed herein by way of example, and this overcoat 508 includes at least one first layer 510, second layer 512, And a central layer 514. By various methods, the first layer, the second layer, and the center layer may be the same, similar, different, or combinations thereof in composition. Further, the first layer, the center layer, and the second layer may be separate layers; all by varying the deposition conditions to form a center layer that has different properties from one of the adjacent layers. May be part of a continuously formed overcoat layer; or a combination thereof.

  In a particularly preferred manner, the first and second layers of the overcoat can have a different composition than the central layer of the overcoat.

As shown in FIG. 5, the overcoat center layer 514 can be defined between the first layer 510 and the second layer 512. The first layer 510 can have a width w ₁ of at least 0.5 nm in the thickness direction from the center layer side closest to the recording layer in the thickness direction. Furthermore the second layer, the first layer may have a width w ₂ of at least 0.5nm in thickness direction from the side opposite to the center layer of the. The thickness of the overcoat 508 may be in the range between 1.25 nm and 5 nm, but may be thicker or thinner.

  The central layer of the overcoat can preferably have a hydrogen content of about 0.1 atomic% to about 0.6 atomic%, more preferably about 0.2 atomic% to 0.4 atomic%, although desired Depending on the embodiment, it may be higher or lower. Further, the central layer can have a carbon content of at least 85 atomic percent, more preferably 90 atomic percent, and even more preferably 95 atomic percent, but may be higher or lower depending on the desired embodiment. In another method, the average value of hydrogen content in a film in a particular region having a carbon content of at least 95 atomic percent in the overcoat is defined as about 0.1 atomic percent to about 0.6 atomic percent. Can be higher or lower, depending on the desired embodiment.

According to various other methods, the mass density of the magnetic recording media and / or magnetic heads of any embodiment described herein is about 3.3 g / cm ³ to about 3. ³ by X-ray reflectometry. It can be determined as 6 g / cm ³ . According to yet another method, the mass density of the overcoat is about 3.3 g / cm ³ ~ about 3.6 g / cm ³ as measured by X-ray reflectance measurement, more preferably from about 3.53 g / ^cm 3 ~ It may be about 3.6 g / cm ³ but may be larger or smaller depending on the desired embodiment.

  FIG. 6 illustrates a method 600 for forming an overcoat according to one embodiment. As an option, the method 600 of the present invention can be implemented with the features of any other embodiments described herein, such as the embodiments described with reference to other figures. However, it should be understood that such method 600 and others provided herein may be used in various applications and / or may or may not be explicitly described in the illustrative embodiments described herein. Can be used in sorting. Further, the method 600 provided herein can be used in any desired environment.

Referring now to FIG. 6, the method 600 includes forming an overcoat on at least one of the magnetic layer of the magnetic medium and the side of the read element facing the medium, where the overcoat is sp ² bonded. Is an amorphous carbon film having a ratio of sp ³ bonds to (sp ³ / (sp ² + sp ³ )) of at least 0.5, and the hydrogen content in the film in the central layer in the overcoat film thickness direction is It is in the range of 0.1 atomic% to 0.6 atomic%. See operation 602.

Referring to operation 604, the hydrogen content of the overcoat is in a preferred range by adjusting the hydrogen gas flow into the film deposition chamber during overcoat deposition and adjusting the hydrogen gas pressure in the film deposition chamber. Adjusted in. In one preferred method, when the overcoat is formed, the range of hydrogen gas pressure in the film deposition chamber of approximately 3.0 × ¹⁰ -2 Pa to about 6.0 × ¹⁰ -2 Pa, and more preferably It can be specified in the range of about 4.5 × 10 ⁻² Pa to about 5.5 × 10 ⁻² Pa, but may be higher or lower depending on the desired embodiment.

  According to one illustrative embodiment that is in no way intended to limit the present invention, the hydrogen content in the membrane can be measured by high resolution elastic recoil detection (HR-ERDA), which is A highly sensitive recoil detection and analysis method for hydrogen analysis targeting hydrogen from elastic recoil detection. In the corresponding manufacturing method for forming the overcoat of the magnetic recording medium and the magnetic head, the hydrogen content in the overcoat can be adjusted to the preferred hydrogen content range as described above. According to one of the methods, the manufacturing method adjusts the hydrogen content by adjusting the hydrogen gas flow supplied from the outside into the film deposition chamber during film deposition and adjusting the hydrogen gas pressure in the film deposition chamber. Can be adjusted.

  According to various methods, the method for producing the ultra-hard amorphous carbon film is not particularly limited, and may be a method in which the hydrogen content can be adjusted within a very small range, preferably within the aforementioned range. According to one method, this may be possible by including a very small amount of hydrogen in the carbon film by supplying a small amount of hydrogen gas into the film deposition chamber during film deposition. Further, various methods such as, but not limited to, filtered cathodic vacuum arc (FCVA) methods that can be used to form ultra-hard amorphous carbon films with small amounts of particles by including a magnetic field filter. A film can be formed by the method.

  While not wishing to limit the scope of the present invention, illustrative examples are described below, which involve small amounts (eg, about 0.1 atomic% to about 0.6 atomic%) of hydrogen in the film. This corresponds to the characteristics of the superhard amorphous carbon film having a thickness of about 2.5 nm. As described above, a small amount of hydrogen in the film can be achieved by supplying a very small amount of hydrogen gas during film deposition and into the film deposition chamber during the manufacturing process.

  According to the first embodiment, which is not intended to limit the present invention, an ultrahard amorphous carbon film having a thickness of about 2.5 nm was formed on a Si single crystal substrate. The amount of hydrogen gas supplied to the inside of the film deposition chamber was varied, and the film density and film hardness with respect to the hydrogen content in the film were evaluated. According to various methods, examples of the substrate include a chemically hardened glass substrate and a substrate having a polished surface after plating, for example, Ni-P on an aluminum alloy substrate. Furthermore, the shape of the substrate can be freely selected according to the desired embodiment.

  Continuing to refer to the first example, the film density was measured by X-ray reflectometry. The obtained measured values are shown in the graph of FIG. 7, where the horizontal axis represents the hydrogen content in the film, and the vertical axis represents the film density. According to this result shown in FIG. 7, the film density is improved in the region where the hydrogen content in the film is about 0.1 atomic% to about 0.6 atomic%. Further, the region 702 having a hydrogen content of about 0.2 atomic% to about 0.4 atomic% has a film density of about 20% as compared with the conventional film of the region 701 formed without supplying hydrogen. Improved.

  Referring now to FIG. 8, there is shown a measurement of film hardness measured using the nanoindenter method. In the graph shown in FIG. 8, the horizontal axis represents the hydrogen content in the film, and the vertical axis represents the film hardness. According to the results shown in the graph, in the region where the hydrogen content in the film is about 0.1 atomic% to about 0.6 atomic%, the film hardness is improved similarly to the film density shown in FIG. . Further, the region 704 having a hydrogen content of about 0.2 atomic% to about 0.4 atomic% has a film hardness of about 10% as compared with the conventional film of the region 703 formed without supplying hydrogen. Improved.

  According to the second example, a film structure similar to that used in the first example was used, but with different hydrogen content (0 atomic%, 0.3 atomic%, 2.5 atomic%) in the film. ) Were produced. These samples were heated with a hot plate set to a temperature of 500 ° C., and the residual film thickness of the carbon film was measured with respect to the heating time.

  FIG. 9 shows the measurement of the change in film thickness, and the film thickness was measured using spectroscopic ellipsometry. Furthermore, the hydrogen content of the examples was measured by including high resolution elastic recoil particle detection (HR-ERDA) for hydrogen analysis. Referring to the graph of FIG. 9, the horizontal axis represents the heating time, and the vertical axis represents the film thickness. According to the results shown in FIG. 9, in the case of the sample 705 in which the hydrogen content in the film is 0 atomic% and the sample 706 in which the atomic content is 2.5 atomic%, the heating time of 100 seconds and 450 seconds, It can be seen that it decreases by 80%. In contrast, at a heating time of 450 seconds, the 0.3 atomic% sample 707 has a decrease in film pressure of less than 10%, indicating strong heat resistance.

  From the above results, the carbon film in the region where the hydrogen content in the film is about 0.1 atomic% to about 0.6 atomic% has stronger heat resistance than the carbon film having a hydrogen content outside the above range. It is clear. Thus, according to one preferred method, the film may be an overcoat of a magnetic recording medium and magnetic head for energy-assisted magnetic recording in which heat is generated on the magnetic recording medium and magnetic head. For example, this film can be a thermally assisted magnetic recording where thermal energy is applied from a magnetic head to a magnetic recording medium during recording to facilitate writing, or a microwave where a high frequency AC magnetic field is used to facilitate writing. It may be an overcoat in assisted magnetic recording.

  According to the third embodiment, which is not intended to limit the present invention, an ultra-hard amorphous carbon film having a thickness of about 2.5 nm is deposited on a Si single crystal substrate and a magnetic recording layer. The hydrogen concentration in the carbon film was evaluated by forming on the glass substrate. According to the graph shown in FIG. 10, the evaluation of three ultra-hard amorphous carbon films 708, 709, and 710 having different amounts of hydrogen gas supplied into the film deposition chamber at the time of formation, and the film 711 formed by the CVD method are performed. went.

  FIG. 10 shows measurement of the hydrogen content in the carbon film on the Si substrate. The horizontal axis represents the depth from the upper surface of the overcoat, and the vertical axis represents the hydrogen content. In addition, depth was measured by high resolution elastic recoil particle detection analysis (HR-ERDA) and high resolution Rutherford backscattering spectroscopy (HRRBS) for hydrogen analysis.

  Continuing to refer to the graph of FIG. 10, components in the air are absorbed by the top surface when removed from the vacuum deposition chamber in a region 0.5 nm deep from the top surface. Further, in the 0.5 nm region on the Si substrate side, a mixed layer of the carbon film and the surface layer of the Si substrate is formed, so that a hydrogen content distribution exists in the depth direction. In the region excluding the 0.5 nm layer on the upper surface of the overcoat and the 0.5 nm layer on the substrate side, the hydrogen content in the film is almost constant.

  11A-11B, the measurement of the hydrogen content in the carbon film on the glass substrate formed by depositing the magnetic recording layer is shown graphically. The horizontal axis of the graph represents the depth from the upper surface of the overcoat, and the vertical axis represents the element concentration. Further, three ultra-hard amorphous carbon films 712, 713, and 714 having different amounts of hydrogen gas supplied to the inside of the film deposition chamber at the time of formation, and a film 714 formed by a CVD method were evaluated.

  Similar to the evaluation result of the Si substrate shown in FIG. 10, the hydrogen content has a certain distribution in the depth direction of the film thickness. In the region excluding the 0.5 nm layer on the upper surface side and the 0.5 nm layer on the substrate side of the overcoat thickness, the hydrogen content in the film has a substantially constant value. Combining the results of the first and second examples, the average of the hydrogen content in the film in the region excluding the 0.5 nm layer on the upper surface side and the 0.5 nm layer on the substrate side of the overcoat thickness The film properties are examined by value. Furthermore, the hydrogen content in the film can be monitored and appropriately controlled within an allowable range (0.1 atomic% to 0.6 atomic%).

  According to one embodiment, the overcoat is suitable for controlling very low hydrogen concentrations when composed of ultra-hard amorphous carbon films using physical vapor deposition means using carbon ions. According to various methods, ultra-hard amorphous carbon films can be produced by ion beam vapor deposition, low gas pressure-high current sputtering, etc., or others that will be apparent to those skilled in the art upon reading the description herein. It can be formed by adopting the method.

  In one illustrative embodiment, which is in no way intended to limit the present invention, the vapor deposition apparatus shown in FIG. 12 can be used to form an overcoat using arc discharge. As shown in FIG. 12, a plasma beam 716 formed by an arc discharge device 715 is used as an ion source (described in detail below). A plasma beam 716 is generated from an arc discharge device 715 arranged so that both surfaces of the magnetic disk substrate 717 to be processed can be processed. In particular, when a voltage from the voltage source 727 is applied between the cathode 718 and the anode 719 made of carbon, an arc discharge 720 is generated in a high vacuum atmosphere.

  As a result, the cathode 718 is in a very hot state similar to arc welding, and plasma (eg, a state that produces positively charged carbon ions 721 and electrons 722) is generated from the cathode surface. In addition, the arc current in cathode 718 flows at about 50 amps and arc discharge with an arc voltage of about -20 volts occurs. The generated carbon ions 721 and electrons 722 pass through a curved magnetic field duct 723 for removing droplets generated during arc discharge and transferring plasma, and film deposition in which a magnetic disk substrate 717 to be processed is accommodated. It is introduced into the chamber 725 and is uniformly emitted by the scanning electromagnet 726 onto the magnetic disk substrate 717 to be processed. Further, the magnetic disk substrate 717 to be processed is electrically floating.

  Incident carbon ions are applied with an energy of about 50 eV, and the plasma beam 716 is neutral and irradiates with carbon ions 721 and electrons 722. Since only the cathode 718 made of carbon is used, an ultra-hard amorphous carbon film containing almost no hydrogen is formed. In this embodiment, the magnetic disk substrate 717 to be processed is electrically floating. However, the present invention is not limited to this, and there is no problem even if a substrate biased by the vapor phase growth method is used.

  Continuing to refer to FIG. 12, when the plasma beam 716 is irradiated onto the unprocessed magnetic disk substrate 717, hydrogen gas is supplied from the outside into the film deposition chamber 725. In this case, by using a mass flow controller 729 to adjust the hydrogen gas supply amount, the hydrogen pressure in the film deposition chamber 725 is maintained at a specified pressure, and an ultra-hard amorphous carbon film is obtained. The hydrogen content therein can be adjusted to the desired value.

According to one preferred method, the hydrogen gas pressure in the film deposition chamber 725, can be in the range of about 3.0 × ¹⁰ -2 Pa to about 6.0 × ¹⁰ -2 Pa, the desired Depending on the embodiment, it may be higher or lower. The supplied hydrogen gas is excited by the plasma beam 716 to generate hydrogen radicals, and these radicals are combined with carbon dangling bonds caused by structural irregularities. Furthermore, this can be caused by radicals being taken into the ultra-hard amorphous carbon film. As a result, film density, film hardness, and heat resistance can be increased, thereby achieving a chemically more stable state. In the illustrative embodiment shown in FIG. 12, hydrogen gas was supplied into the film deposition chamber 725, but according to another method, other than the film deposition chamber 725, such as where the hydrogen gas can be excited by the plasma beam 716. Gas can be supplied to the place.

  Note that the methods presented herein for at least some of the various embodiments may be implemented in whole or in part on computer hardware, software, manual work, use of specialized equipment, etc., and combinations thereof. I want to be. In one illustrative method, a magnetic recording device may be included in a magnetic recording medium and / or magnetic head according to any of the embodiments described and / or suggested herein.

  Although various embodiments have been described above, it should be understood that these are provided by way of example only and are not limiting. Accordingly, the breadth and scope of an embodiment of the present invention should not be limited to any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. is there.

DESCRIPTION OF SYMBOLS 100 Disk drive 112 Magnetic disk 113 Slider 114 Spindle 115 Suspension 118 Drive motor 119 Actuator arm 121 Head 122 Disk surface 123 Line 125 Recording channel 127 Actuator 128 Line 129 Controller 200 Support base material 202 Upper layer coating 204 Recording / reproducing head 212 Lower layer 214 Upper layer Coating 216 Substrate 218 Vertical head 302 Upper return pole 304 Trailing shield 306 Main pole 308 Stitch pole 310 Helical coil 312 Helical coil 314 Lower return pole 316 Insulator 318 ABS
322 sensor shield 324 sensor shield 326 sensor 402 upper return magnetic pole 404 trailing shield 406 main magnetic pole 408 stitch magnetic pole 410 loop coil
416 Insulator 418 ABS
422 sensor shield 424 sensor shield 426 sensor 500 magnetic recording medium 502 nonmagnetic substrate 504 ground layer 506 magnetic recording layer 508 overcoat 510 first layer 512 second layer 514 center layer 600 method 602 operation 604 operation 701 region 702 region 703 Region 704 region 705 sample 706 sample 707 sample 708 film 709 film 710 film 711 film 712 film 713 film 714 film 715 arc discharge device 716 plasma beam 717 magnetic disk substrate 718 cathode 719 anode 720 arc discharge 721 carbon ion 7 2 Duct 725 Film deposition chamber 726 Scanning magnet 727 Voltage source 729 Mass flow controller

Claims (21)

A magnetic recording medium:
At least one ground layer on the non-magnetic substrate;
A magnetic recording layer on the ground layer;
Including an overcoat on the magnetic recording layer;
The overcoat is an amorphous carbon film in which a ratio of sp ³ bonds to sp ² bonds (sp ³ / (sp ² + sp ³ )) is at least 0.5, and the overcoat in the film thickness direction of the overcoat A magnetic recording medium, wherein the hydrogen content in the central layer of the overcoat is 0.1 atomic% to 0.6 atomic%.   The central layer of the overcoat is provided between the first layer and the second layer of the overcoat, and the first layer is at least 0. 0 in the film thickness direction from the side closest to the recording layer. 2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium extends 5 nm, and the second layer extends at least 0.5 nm in the film thickness direction from the side opposite to the first layer.   The magnetic recording medium according to claim 2, wherein the first and second layers have a composition different from that of the central layer.   The magnetic recording medium according to claim 1, wherein the amorphous carbon is mainly tetrahedral amorphous carbon.   The magnetic recording medium of claim 1, wherein the central layer has a carbon content of at least 95 atomic percent. Mass density of the overcoat as measured by X-ray reflectance measurement is in the range of ^{3.3g / cm 3 ~3.6g / cm 3} , the magnetic recording medium of claim 1. Mass density of the overcoat as measured by X-ray reflectance measurement is in the range of ^{3.5g / cm 3 ~3.6g / cm 3} , the magnetic recording medium of claim 1.   The magnetic recording medium according to claim 1, wherein a hydrogen content in a central layer of the overcoat in a film thickness direction of the overcoat is 0.2 atomic% to 0.4 atomic%. Magnetic data storage system:
At least one magnetic head;
A magnetic medium according to claim 1;
A drive mechanism for passing the magnetic medium above the at least one magnetic head;
A magnetic data storage system comprising: a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head. Magnetic head:
A reproducing element;
The reproducing element includes an upper overcoat on the side facing the medium, and the overcoat has a ratio of sp ³ bonds to sp ² bonds (sp ³ / (sp ² + sp ³ )) of at least 0.5. It is an amorphous carbon film, and the hydrogen content in the amorphous carbon film of the central layer of the overcoat in the film thickness direction of the overcoat is 0.1 atomic% to 0.6 atomic% A magnetic head.   The central layer of the overcoat is provided between the first layer and the second layer of the overcoat, and the first layer is at least 0. 0 in the film thickness direction from the side closest to the reproducing element. The magnetic head according to claim 10, wherein the magnetic head extends 5 nm, and the second layer extends at least 0.5 nm in the film thickness direction from the side opposite to the first side.   The magnetic head according to claim 11, wherein the first and second layers have a composition different from that of the central layer.   The magnetic head according to claim 10, wherein the amorphous carbon is mainly tetrahedral amorphous carbon.   The magnetic head of claim 10, wherein the central layer has a carbon content of at least 95 atomic percent. Mass density of the overcoat as measured by X-ray reflectance measurement is in the range of ^{3.3g / cm 3 ~3.6g / cm 3} , the magnetic head according to claim 10. Mass density of the overcoat as measured by X-ray reflectance measurement is in the range of ^{3.5g / cm 3 ~3.6g / cm 3} , the magnetic head according to claim 10.   The magnetic head according to claim 10, wherein a hydrogen content in a central layer of the overcoat in a film thickness direction of the overcoat is 0.2 atomic% to 0.4 atomic%. Magnetic data storage system:
At least one magnetic head according to claim 10;
With magnetic media;
A drive mechanism for passing the magnetic medium above the at least one magnetic head;
A magnetic data storage system comprising: a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head. Forming an overcoat on at least one of the magnetic layer of the magnetic medium and the side of the read element facing the medium, the overcoat comprising a ratio of sp ³ bonds to sp ² bonds (sp ³ / (Sp ² + sp ³ )) is an amorphous carbon film of at least 0.5, and the hydrogen content in the amorphous carbon film of the central layer of the overcoat in the film thickness direction of the overcoat Including from 0.1 atomic% to 0.6 atomic%,
The hydrogen content of the overcoat is adjusted within the range by adjusting the hydrogen gas flow into the film deposition chamber during deposition of the overcoat and adjusting the hydrogen gas pressure in the film deposition chamber. The way it is. Wherein the hydrogen gas pressure in the film deposition chamber is in the range of ^{3.0 × 10 -2 Pa~6.0 × 10 -2} Pa when overcoating is formed The method of claim 19 . Wherein the hydrogen gas pressure in the film deposition chamber is in the range of ^{4.5 × 10 -2 Pa~5.5 × 10 -2} Pa when overcoating is formed The method of claim 19 .

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